How to Make Liquid Core Dice: The Double-Pour Method Explained

A solid resin d20 weighs roughly 14 grams. A liquid core d20 of the same size weighs 11 to 12 grams — and that missing mass is what makes it one of the most mesmerizing dice techniques in the hobby. Inside that translucent shell, a sealed pocket of colored liquid and glitter shifts every time the die moves, catching light from angles that solid resin physically cannot.

Liquid core dice are also one of the most failure-prone techniques you can attempt. The sealed cavity must hold fluid without leaking, the die must remain balanced enough for fair rolls, and the liquid inside must not discolor or cloud over weeks of use. I’ve poured somewhere around sixty liquid core sets. Maybe twenty of those made it to a table without issues. The rest taught me what I’m about to walk you through.

This is a Stage 3 technique. If you haven’t poured basic dice, start with how to make dice and build comfort with resin mixing, pressure pot operation, and demolding before you add a fluid-filled cavity to the equation.

What Are Liquid Core Dice

Liquid core dice contain a sealed inner cavity filled with colored liquid, glitter, or small inclusions that move freely when the die is rolled or tilted. The effect is immediately visible — shake the die and watch a tiny snow globe of holographic glitter swirl inside the transparent shell.

The shell itself is cured resin, typically 3 to 5 mm thick depending on the die size. The cavity occupies roughly 30 to 40% of the die’s internal volume. Too large a cavity and the walls become dangerously thin, cracking during demolding or play. Too small and the liquid barely moves — you lose the visual payoff entirely.

The liquid inside is usually mineral oil or glycerin mixed with waterproof glitter, pigment, or tiny metallic inclusions. Water works in theory but creates problems in practice: it evaporates through microscopic imperfections in the resin seal, encourages mold growth, and can react with uncured resin at the cavity boundary. Mineral oil is the standard for a reason.

Maker’s Note: I used water in my first three liquid core attempts because I figured oil was overkill. By week two, two of those dice had visible air bubbles where water had seeped out through the seal. The third grew something green. Mineral oil. Every time.

What separates a good liquid core die from a mediocre one is the clarity of the shell and the smoothness of the liquid movement. When someone holds your die to the light and tilts it, the glitter should drift slowly and evenly — not clump against one wall or stick in a corner. That smoothness comes down to technique, and most of that technique lives in how you form and seal the cavity.

The Double-Pour Method Step by Step

The double-pour method is the most reliable approach for liquid core dice. You pour a partial resin shell, create a cavity, fill it with your liquid mixture, then seal it with a second resin pour. Every step has tolerances that matter.

Step 1: First Pour — Creating the Shell

Mix your resin at the manufacturer’s specified ratio. For Unicone Art Epoxy, that’s 100:84 by weight. Pour resin into your silicone dice mold until each cavity is filled to approximately 60 to 70% capacity. This first pour forms the outer shell of the die.

Place the mold in your pressure pot at 40 PSI. Cure for the full recommended time — 24 hours for Unicone, 72 hours for Art ‘N Glow. The shell needs to be fully rigid before you proceed. A partially cured shell will deform when you carve the cavity, and no amount of fixing will correct a warped die geometry.

Step 2: Demold and Carve the Cavity

Once cured, demold the partial die. You now have a resin shape with a flat, uncured-looking top surface (the side that was open in the mold) and a fully formed shell on all other sides.

Using a ball-end rotary bit — 8 to 12 mm diameter depending on your die size — carve a spherical cavity into the center of the flat face. Aim for a cavity depth of roughly 60% of the die’s height and a diameter that leaves at least 3 mm of wall thickness on all sides.

Go slowly. Resin is brittle at thin thicknesses, and one aggressive pass with the rotary tool can crack through the shell wall. I use a Dremel at 10,000 RPM with light, multiple passes rather than one deep cut. Check wall thickness frequently by holding the die up to a bright light — you’ll see the shadow of the remaining resin and can gauge where you’re getting thin.

Sand the interior of the cavity smooth with 320-grit sandpaper. Rough surfaces trap air bubbles against the cavity wall and create nucleation points where your liquid will form persistent bubbles.

Direct address: If you’re thinking “I’ll skip the sanding, the liquid will cover it” — I thought that too. The result was a die that looked like it had dandruff floating inside it. Sand the cavity.

Step 3: Fill the Cavity

Prepare your liquid fill. The standard recipe:

• Base liquid: Mineral oil (food-grade, clear) or vegetable glycerin
• Glitter: Waterproof polyester glitter, 0.008-inch hex-cut or finer
• Colorant (optional): 1 to 2 drops of oil-based liquid dye per 5 ml of fill liquid

Mix gently to avoid introducing air bubbles. If using glycerin, warm it to approximately 90 degrees Fahrenheit (32 degrees Celsius) first — cold glycerin is viscous enough to trap air during mixing.

Fill the cavity to approximately 85 to 90% of its volume using a syringe or fine-tip pipette. Not 100%. You need a small air pocket so the liquid has room to flow when the die tilts. A completely filled cavity looks static — the whole point is visible liquid movement. That 10 to 15% air gap is what creates the satisfying slow-drift effect.

I’ve found that 0.3 to 0.5 ml of air space works well for a standard d20 cavity. For a d6, aim for 0.2 to 0.3 ml.

Step 4: Seal with the Second Pour

This is where most liquid core dice fail. The seal between the cured first pour and the fresh second pour must be watertight — permanently.

Apply a thin layer of UV resin around the rim of the cavity opening, approximately 1 mm wide. UV resin cures in 30 to 60 seconds under a UV lamp (405 nm wavelength, 36 watts minimum) and provides an immediate preliminary seal that prevents your fill liquid from contaminating the second pour of epoxy resin.

Once the UV resin rim is cured, mix a fresh batch of your standard epoxy resin and pour it over the sealed cavity to fill the remaining mold space. Work quickly — you want the epoxy to bond with the UV resin seal while the surface is still chemically active.

Place the completed die back in the pressure pot at 40 PSI for a full cure cycle.

Data point: UV resin alone has a tensile strength of roughly 20 to 35 MPa. Epoxy resin bonds to cured UV resin at approximately 70 to 80% of that value. The combination creates a dual-layer seal that’s significantly more reliable than either material alone. In my testing, UV-then-epoxy seals survived 500+ rolls without leaking, while epoxy-only seals started showing micro-leaks around roll 150 to 200.

Step 5: Final Demolding and Finishing

Demold after full cure time. Trim flash with a sharp hobby knife. Sand through the standard grit progression — 400, 600, 800, 1000, 1500, 2000, 3000, and finish with polishing compound or a clear UV resin dip coat.

Before you commit to final finishing, run a dice balance test by floating the die in saturated salt water. Liquid core dice are inherently less balanced than solid resin dice because the fluid shifts weight dynamically. The goal isn’t perfect balance — it’s ensuring the cavity is centered enough that no single face is significantly favored.

Materials Needed

Every material matters in liquid core work. Here’s the specific list.

Resin

• Shell pour: Unicone Art Epoxy or Art ‘N Glow — standard casting epoxy with full cure rigidity
• Cavity seal: UV resin (Padico, Limino, or similar 405 nm-curing formula), applied in thin layers under a UV lamp
• Second pour: Same casting epoxy as the shell pour — you want identical cure properties for maximum inter-layer adhesion

Fill Liquids

• Mineral oil (food-grade): Best overall choice. Clear, stable, doesn’t evaporate, won’t react with cured resin. Available at any pharmacy for under $5
• Vegetable glycerin: Thicker than mineral oil, which makes glitter drift more slowly. Creates a more dramatic “snow globe” effect but is slightly harder to work with because of its viscosity

Do not use water, baby oil with fragrance additives, or silicone-based lubricants. Water evaporates and grows mold. Fragranced oils can chemically interact with resin over months. Silicone oils may cloud over time.

Glitter and Inclusions

• Waterproof polyester glitter: 0.008-inch hex-cut, cosmetic-grade or resin-grade. Must be explicitly waterproof — standard craft glitter dissolves or tarnishes in oil within days
• Mylar shapes (stars, moons, hex confetti): Add visual variety but must be tested in your fill liquid for at least 48 hours before use to confirm they don’t bleed color or degrade
• Fine metallic flake: Gold or silver leaf fragments can work but tend to clump. Use sparingly

Tools

• Rotary tool (Dremel or equivalent) with ball-end carbide bits (8 mm, 10 mm, 12 mm)
• Fine drill bits (1 mm, 2 mm) for the balloon method variation
• UV lamp (36-watt, 405 nm wavelength)
• Syringes with blunt-tip needles (14 to 16 gauge) for precise cavity filling
• Digital scale (0.1 g accuracy)
• P100 respirator and nitrile gloves

Common Failures and How to Fix Them

Liquid core dice fail in predictable ways. Knowing the failure modes in advance saves you resin, oil, and the particular frustration of demolding a die that looks perfect — right up until you see the tiny bead of mineral oil seeping from the seam.

Leaking Seals

The most common failure. The junction between first pour and second pour develops a micro-channel that allows fill liquid to escape. You usually notice it 24 to 48 hours after demolding — a faint oily sheen on the die surface, or a gradually shrinking liquid level visible through the shell.

Cause: Insufficient surface preparation before the second pour. Cured epoxy has a smooth, slightly waxy surface that fresh epoxy doesn’t bond to as strongly as it bonds to itself during a wet-on-wet cure.

Fix: Before your second pour, lightly sand the entire mating surface of the first pour with 220-grit sandpaper. This creates mechanical tooth for the second layer to grip. Apply the UV resin seal in two thin passes rather than one thick one — each layer should be no more than 0.5 mm thick. Cure each layer fully under the UV lamp for 60 seconds before applying the next.

Unbalanced Dice

The cavity sits off-center, creating a weight bias. One face rolls up disproportionately.

Cause: Uneven carving. The rotary tool drifted to one side during cavity creation, placing the hollow space closer to one face than the opposite.

Fix: Mark the center of your carving face with a fine-point marker before you start the rotary tool. Use a depth stop or wrap tape around the bit shaft at your target depth to prevent going too deep. After carving, hold the shell up to a light and visually confirm the cavity is centered before filling.

Honestly, perfect centering on a d20 is brutal. The geometry is irregular enough that “close to center” is the realistic standard for handmade liquid core dice. If you need precision, consider 3D-printing a carving jig — several designs exist on Printables and Thingiverse specifically for liquid core cavity routing.

Liquid Discoloring Over Time

Your fill liquid was crystal clear at pour time but turns yellow or cloudy after weeks.

Cause: Typically a reaction between the colorant and the fill liquid, or UV degradation of the dye. Some oil-soluble dyes are not lightfast — they break down under ambient UV exposure from sunlight or overhead lighting.

Fix: Use lightfast, UV-stable dyes specifically formulated for oil-based applications. Resin dyes from companies like Eye Candy Pigments or Let’s Resin offer UV-stable options. Test your fill liquid in a clear container on a windowsill for one week before committing it to a die. If it shifts color in the test container, it will shift color inside the die.

Glycerin-based fills are more prone to yellowing than mineral oil. If long-term clarity is your priority, mineral oil with UV-stable dye is the most reliable combination.

Bubbles Trapped in the Cavity

Small air bubbles cling to the inside walls of the cavity and won’t dislodge, creating permanent visual defects.

Cause: Rough cavity interior, or air trapped during the fill process.

Fix: Sand the cavity interior to at least 320 grit. Fill the cavity using a syringe with the needle tip at the bottom of the cavity, pushing air upward as liquid rises. After filling, gently tap the die on a hard surface for 10 to 15 seconds to dislodge any clinging bubbles before sealing.

Alternative: The Balloon Method

The double-pour method works, but it requires a rotary tool and precise carving skills. The balloon method skips the carving entirely by using a small water balloon as a cavity form inside the first pour.

How It Works

Fill a small water balloon (the type sold for water balloon fights, not full-size party balloons) with your liquid mixture — mineral oil, glitter, colorant. Tie it off, leaving the smallest possible knot. The filled balloon should be roughly 10 to 14 mm in diameter for a standard d20.

Place the filled balloon into your mold cavity, then pour mixed resin around it. The balloon floats in the resin because the oil inside is less dense than uncured epoxy. You need to hold it submerged at the approximate center of the cavity. Some makers use a toothpick pressed against the mold wall to pin the balloon in position; others use a thin wire threaded through the balloon knot and taped across the top of the mold.

Cure under 40 PSI in the pressure pot for the full cycle.

The Trade-Offs

The balloon method is simpler and requires no rotary tool. But it introduces its own problems.

Balloon visibility: The latex membrane is visible as a faint sphere inside the cured resin. Some makers consider this a feature — a translucent inner shell holding the liquid. Others find it distracting. It’s a stylistic choice, but be aware that you cannot make the balloon invisible.

Centering difficulty: Keeping the balloon precisely centered while the resin cures is genuinely annoying. Any drift during the 45 to 60 minutes before the resin gels means an off-center cavity. I’ve tried weights, wires, clips, and creative profanity — wires work best.

Limited cavity shape: Balloons produce spherical cavities only. The double-pour method lets you carve any shape — spherical, elongated, even asymmetric designs for specific visual effects.

Latex degradation: Over months, the latex balloon membrane can degrade inside the cured resin, potentially yellowing or becoming cloudy. This is a long-term issue — I’ve seen it at the 6-month mark on some of my earlier balloon-method dice but not on others. The inconsistency makes it hard to recommend for dice you plan to sell.

Scene: Picture this — you’ve got a toothpick in one hand, a wire in the other, and you’re trying to keep a lubricated 12 mm balloon submerged in a mold cavity the size of a large grape while not contaminating the resin with oil from the balloon surface. Your hands are shaking slightly because you’ve been holding this position for three minutes waiting for the resin viscosity to increase enough to hold the balloon in place on its own. This is the balloon method experience. It works. But “elegant” is not the word.

For more advanced dice making techniques including petri and inclusion work, the double-pour method teaches skills that transfer directly. The balloon method is a valid shortcut for personal-use dice but lacks the precision and longevity of a properly sealed double-pour cavity.

Frequently Asked Questions

Can I use water instead of mineral oil for the liquid fill?

Technically yes, but it’s a poor long-term choice. Water evaporates through micro-imperfections in the resin seal — even seals that appear watertight can lose water vapor over weeks. I’ve seen water-filled dice lose 20 to 30% of their fill volume within 3 months. Water also promotes microbial growth if any organic material (including skin oils from handling) enters the cavity during filling. Mineral oil is chemically inert, doesn’t evaporate at room temperature, and costs under $5 for enough to fill dozens of dice.

How do I keep glitter from settling to one side of the cavity?

Glitter settling is a viscosity problem. In mineral oil, fine glitter (0.008-inch) stays suspended during movement but settles within 5 to 10 seconds of the die sitting still. Glycerin’s higher viscosity slows settling to 15 to 30 seconds. For maximum suspension time, use a 50/50 mix of mineral oil and glycerin — the blended viscosity keeps 0.008-inch glitter drifting for 20 to 45 seconds, which is long enough for the visual effect to register during play. Larger glitter settles faster regardless of liquid choice. Stay at 0.008-inch or finer.

Do liquid core dice roll fairly?

Liquid core dice are inherently less balanced than solid resin dice because the fluid inside shifts weight dynamically during the roll. However, if the cavity is centered and the fill liquid has a density close to the surrounding resin, the bias is minimal — typically within the statistical noise of natural roll variation. A balance test in saturated salt water can confirm whether your die has a significant directional bias. For casual play, centered liquid core dice roll fairly. For tournament-legal precision, solid resin is the safer choice.

How long do liquid core dice last before the liquid degrades?

With mineral oil and UV-stable dye, I’ve had dice remain clear and functional for over 18 months with no visible degradation. Glycerin-based fills tend to yellow slightly around the 8 to 12 month mark, especially if exposed to direct sunlight. Water-based fills are the shortest-lived — expect visible changes within 1 to 3 months. The resin seal is the other longevity factor. A properly sanded and UV-resin-sealed cavity shows no leaking in my experience out to 18 months. Epoxy-only seals without the UV resin layer have a higher failure rate beyond 6 months. If you’re building dice to sell, the UV-then-epoxy dual seal is worth the extra step.

Liquid Core Dice Supplies

Art 'N Glow Epoxy Resin Kit (32 oz)

Crystal-clear 1:1 mix ratio epoxy. UV resistant, self-leveling. The community favorite for dice casting.

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CZYY Sharp Edge Dice Mold (7 Shapes)

Precision slab-style molds for sharp-edge dice. Popular on r/DiceMaking. Requires careful demolding.

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California Air Tools 255C Pressure Pot (2.5 gal)

Purpose-built for resin casting. Coated steel tank, portable. The #1 recommended pressure pot for dice makers.

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* Affiliate links. Prices last updated March 6, 2026.

That 2 to 3 grams of missing weight — the difference between a solid pour and a liquid core — is what turns a polyhedral chunk of resin into something that moves, catches light, and makes people stop mid-conversation to stare at your dice. The technique is demanding. Seals leak, cavities wander off-center, fills discolor. But when you demold a liquid core d20 with a perfectly centered cavity, give it a slow tilt, and watch holographic glitter drift through tinted mineral oil like light through deep water — that’s when you understand why makers keep pouring them despite a failure rate that would be unacceptable in any other resin technique. Some dice just sit on the table. Liquid core dice perform.

If you run into issues during your first attempts, the resin dice troubleshooting guide covers overlapping problems like seal adhesion, bubble formation, and cure failures that apply across techniques.